The plane was one of several owned by the 61-year-old composer and no one has heard from him since the crash, but authorities did not immediately identify him as the pilot who died. No one else was on board.

Horner's attorney, Jay Cooper, said Tuesday that people who fuelled the plane at an airport in Camarillo confirmed that Horner took off in the aircraft.

Horner's agents, Gorfaine and Sam Schwartz, issued a statement Tuesday saying he died, although official confirmation could take several days while the Ventura County coroner works to identify the remains found at the crash site.

James Cameron, Ron Howard, Celine Dion and many other celebrities are remembering the 61-year-old as a talented man and a good friend.

"We will always remember his kindness and great talent that changed my career," Dion said.

&quot;Shaken by the tragic death of James Horner. We send our prayers and deepest condolences to his family and friends.&quot; <a href="http://t.co/6ngV2fcIaf">pic.twitter.com/6ngV2fcIaf</a>

Cameron and Jon Landau, who respectively directed and produced Avatar, said in a statement: "We have lost not only a great team-mate and collaborator, but a good friend. James's music affected the heart because his heart was so big."

Horner was nominated for 10 Academy Awards in his career, winning two for 1997's best picture, Titanic.

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He composed the film's score and its enduring theme song, My Heart Will Go On, sung by Dion. His scores for Alien, Apollo 13, Field of Dreams, Braveheart, A Beautiful Mind, House of Sand and Fog and Avatar also earned Oscar nods, as did his original song, Somewhere Out There, from An American Tail.

Among his other credits were Glory, Legends of the Fall, two films in the Star Trek franchise during the 1980s, The Hunt for Red October, and The Perfect Storm. His name is also attached to films yet to be released, including the July release Southpaw.

My Heart Will Go On hit No. 1 around the world and become the best-selling single of 1998. The National Endowment for the Arts and the Recording Industry Association of America included it among its "Songs of the Century" rankings.

James Horner holds up two Oscars after winning for Best Original Song and Original Dramatic Score for his work on the movie Titanic at the 70th Annual Academy Awards in 1998. (Reuters )

A pianist since age five, Horner studied at the Royal Academy of Music in London and the University of Southern California, eventually earning graduate degrees at the University of California, Los Angeles.

He got his start composing for movies by scoring shorts for the American Film Institute. His first commercial credits came from Roger Corman, who hired Horner to score several films in the 1980s, including Humanoids from the Deep and Battle Beyond the Stars.

Horner discussed his approach to making music while working on Avatar.

"To me, writing and composing are much more like painting, about colours and brushes," he told the Los Angeles Times in 2009. "I don't use a computer when I write and I don't use a piano. I'm at a desk writing and it's very broad strokes and notes as colors on a palette. I think very abstractly when I'm writing. Then as the project moves on it becomes more like sculpting."

Horner was known for including passages from his earlier compositions and from other composers in his work.

Horner's other collaborators included George Lucas, Steven Spielberg and Oliver Stone. Horner worked many times with Cameron, with whom he often discussed the role of music in film.

"My job ... is to make sure at every turn of the film it's something the audience can feel with their heart," Horner said in 2009. "When we lose a character, when somebody wins, when somebody loses, when someone disappears — at all times I'm keeping track, constantly, of what the heart is supposed to be feeling."

Horner's single-engine plane crashed in the Los Padres National Forest. It was an S-312 Tucano MK1 turboprop with two seats, according to Ian Gregor, spokesman for the Federal Aviation Administration.